column-headers: sync up new column headers styling for dark variation
column-headers: sync up new column headers styling for dark variation

ChrisCummins/gnome-themes-standard,Distrotech/gnome-themes-standard,ChrisCummins/gnome-themes-standard,DoctorJellyface/gnome-themes-standard,ChrisCummins/gnome-themes-standard,ChrisCummins/gnome-themes-standard,DoctorJellyface/gnome-themes-standard,rgcjonas/adwaita-semidark,rgcjonas/adwaita-semidark,Distrotech/gnome-themes-standard,ChrisCummins/gnome-themes-standard,rgcjonas/adwaita-semidark,rgcjonas/adwaita-semidark